Powertop wont work, it says every time I start it

Bug #855348 reported by johnlon on 2011-09-21
This bug affects 17 people
Affects Status Importance Assigned to Milestone
powertop (Fedora)
Fix Released
powertop (Ubuntu)

Bug Description

loaded 14 prior measurements cannot load from file /var/cache/powertop/saved_parameters.powertop and that happens every time I try to use it

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: powertop 1.97-2
ProcVersionSignature: Ubuntu 3.0.0-11.18-generic 3.0.4
Uname: Linux 3.0.0-11-generic i686
NonfreeKernelModules: wl
ApportVersion: 1.23-0ubuntu1
Architecture: i386
Date: Wed Sep 21 09:29:39 2011
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Beta i386 (20110909)
 PATH=(custom, no user)
SourcePackage: powertop
UpgradeStatus: No upgrade log present (probably fresh install)

Description of problem:
everytime i start powertop it complains like this:

Loaded 75 prior measurements
Cannot load from file /var/cache/powertop/saved_parameters.powertop

i checked the file. its there but it isnt.
ll /var/cache/powertop/saved_parameters.powertop
ls: cannot access /var/cache/powertop/saved_parameters.powertop: No such file or directory
[root@laptop powertop]# cd /var/cache/powertop/
[root@laptop powertop]# ll
total 92K
-rw-r--r-- 1 root root 92K Apr 19 19:47 saved_results.powertop

drwx------ 2 root root 4.0K Apr 19 19:00 powertop

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1.start powertop
2.quit to view full error message

Actual results:
no idea if it is harmful to the program

Expected results:
no error messages

Additional info:

ok - so the file is missing - why is powertop asking for a non-existent file ?

johnlon (jakewc2) wrote :
Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in powertop (Ubuntu):
status: New → Confirmed
Vincent (vinnl) wrote :

I get the same message, it does, however, work:

$ sudo powertop
Loaded 11 prior measurements
Cannot load from file /var/cache/powertop/saved_parameters.powertop
Leaving PowerTOP

It doesn't save the tunables I switched, though.

Oscar Tiderman (oscar-tiderman) wrote :

I had the same complaint from powertop, just 'sudo touch' -ed the file and complaint's gone. It still doesn't seem to write anything to the file though.

I have the problem too.

It seems you didn't run the initial calibration. If you are running on NB, disconnect AC and run:
# powertop --calibrate
Then let the powertop to collect enough data (approx. 1 hour). After then it will show approx. wattage for each process / device. When you exit, it saves its state and the message should gone.

It is only warning and it should be ignored, if it annoy you and you can't/don't want to run the calibration just:
# touch /var/cache/powertop/saved_parameters.powertop

Maybe the wording of the message is a bit confusing, I will forward this to upstream.

> It is only warning and it should be ignored

Of course s/should/can/

Created attachment 539750
Proposed patch

powertop-1.98-2.fc16 has been submitted as an update for Fedora 16.

powertop-1.98-2.fc15 has been submitted as an update for Fedora 15.

Package powertop-1.98-2.fc16:
* should fix your issue,
* was pushed to the Fedora 16 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing powertop-1.98-2.fc16'
as soon as you are able to.
Please go to the following url:
then log in and leave karma (feedback).

*** Bug 751578 has been marked as a duplicate of this bug. ***

Calibration Now Working Thank you

root@Fedora16Verne onuralp# powertop --calibrate
Loaded 0 prior measurements
Starting PowerTOP power estimate calibration
Calibrating idle
Calibrating: disk usage
Calibrating backlight
.... device /sys/class/backlight/intel_backlight/brightness
.... device /sys/class/backlight/acpi_video0/brightness
.... device /sys/class/backlight/acpi_video1/brightness
.... device /sys/class/backlight/acpi_video2/brightness
Calibrating idle
Calibrating: CPU usage on 1 threads
Calibrating: CPU usage on 4 threads
Calibrating: CPU wakeup power consumption
Calibrating: CPU wakeup power consumption
Calibrating: CPU wakeup power consumption
Calibrating USB devices
.... device /sys/bus/usb/devices/usb1/power/control
.... device /sys/bus/usb/devices/usb2/power/control
.... device /sys/bus/usb/devices/1-1/power/control
.... device /sys/bus/usb/devices/2-1/power/control
.... device /sys/bus/usb/devices/1-1.3/power/control
.... device /sys/bus/usb/devices/1-1.4/power/control
.... device /sys/bus/usb/devices/2-1.5/power/control
.... device /sys/bus/usb/devices/2-1.1/power/control
Calibrating radio devices
.... device /sys/class/rfkill/rfkill4/soft
.... device /sys/class/rfkill/rfkill0/soft
.... device /sys/class/rfkill/rfkill1/soft
.... device /sys/class/rfkill/rfkill4/soft
.... device /sys/class/rfkill/rfkill0/soft
.... device /sys/class/rfkill/rfkill1/soft
Finishing PowerTOP power estimate calibration
Parameters after calibration:

Parameter state
Value Name
 0.50 alsa-codec-power (15)
 0.00 backlight (4)
 0.00 backlight-boost-100 (8)
 0.00 backlight-boost-40 (6)
 0.00 backlight-boost-80 (7)
 0.00 backlight-power (5)
100.00 base power (45)
 1.56 cpu-consumption (3)
39.50 cpu-wakeups (2)
 0.00 disk-operations (48)
 0.20 disk-operations-hard (47)
 0.56 gpu-operations (46)
 0.00 p1p1-link-100 (21)
 0.00 p1p1-link-1000 (22)
 0.00 p1p1-link-high (23)
 0.00 p1p1-packets (24)
 0.00 p1p1-powerunsave (20)
 0.00 p1p1-up (19)
 0.00 radio:hci0 (16)
 0.00 radio:hp-wifi (17)
 0.00 radio:phy0 (18)
 0.00 runtime-0000:00:00.0 (31)
 0.00 runtime-0000:00:01.0 (32)
 0.00 runtime-0000:00:02.0 (33)
 0.00 runtime-0000:00:1a.0 (34)
 0.00 runtime-0000:00:1b.0 (35)
 0.00 runtime-0000:00:1c.0 (36)
 0.00 runtime-0000:00:1c.1 (37)
 0.00 runtime-0000:00:1d.0 (38)
 0.00 runtime-0000:00:1f.2 (39)
 0.00 runtime-0000:00:1f.3 (40)
 0.00 runtime-0000:00:1f.6 (41)
 0.00 runtime-0000:01:00.1 (42)
 0.00 runtime-0000:02:00.0 (43)
 0.00 runtime-0000:03:00.0 (44)
 0.10 usb-device-0408-03b2 (13)
 0.10 usb-device-046d-c526 (12)
 0.10 usb-device-12d1-1037 (14)
 0.10 usb-device-148f-1000 (11)
 0.10 usb-device-1d6b-0002 (9)
 0.10 usb-device-8087-0020 (10)
 0.00 wlan0-link-100 (27)
 0.00 wlan0-link-1000 (28)
 0.00 wlan0-link-high (29)
 0.00 wlan0-packets (30)
 0.00 wlan0-powerunsave (26)
 0.00 wlan0-up (25)

Score: 0.0 ( 0.0)
Guess: 102.6
Actual: 0.0
Leaving PowerTOP

powertop-1.98-2.fc16 has been pushed to the Fedora 16 stable repository. If problems still persist, please make note of it in this bug report.

powertop-1.98-2.fc15 has been pushed to the Fedora 15 stable repository. If problems still persist, please make note of it in this bug report.

A patch was proposed at:
It says that if the file exists then it will write to it.

It seems that a powertop --calibrate may be required after an empty file is created to get benifit from it. E.g. "sudo touch /var/cache/powertop/saved_parameters.powertop" as suggested. Note, you want to make sure of the permissions of this file, especially on multi-user systems.

powertop --calibrate turns things on and off to test power usage. One suggestion said to let it run for an hour or so after and it will show estimates in a new column.

Changed in powertop (Fedora):
importance: Unknown → Undecided
status: Unknown → Fix Released
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